This volume comprises the papers presented at the Session on Wood Products Pathology during the 2nd International Congress on Plant Pathology on 10th – 12th September 1973 in Minneapolis/USA. The topics were dealt with under four heads, viz. Interaction of Microorganisms during Wood Decay, Bacterial Degradation of Wood, Decay of Resistant Wood and Enzymatic Mechanisms of Deterioration Process, followed by a Discussion Session on Extension: an obli- gation of all Wood Products Pathologists -. Thanks to the cooperation of the authors all the papers could be compiled in this volume. The conference gave an unique possibility to discuss in depth the principles of wood decay by microorganisms from the various angles. The chapters give detailed information on the current progress and problems in wood products pathology. They are therefore collected together in this volume so that people interested in this field will have immediate access to the material and ideas presented. The topic of this Session, the degradation of wood by fungi and bacteria, has become more and more important during the last years. Wood is the only renewable natural resource and raw material of man so that it must be preserved against unwanted deterioration. On the other hand, its natural decomposition does not lead to any harmful products but only to carbondioxide and water. Both aspects have been dealt with in this volume. Hamburg, March 1975 Walter Liese Contributors A.F.BRAVERY, Building Research Establishment, Princes Risborough Laboratory, Princes Risborough, U.K.